Secret-signaling apparatus for automatically enciphering and deciphering messages



Jan, 1,3, 1925.

W. F. FRIEDMAN SECRET SIGNALING APPARATUS FOR AUTOMATICALLY ENCIPHERNG AND DECIPHERING MESSAGES Filed April 14.

Jan. 13, 1925- 1,522,775

W. F. FRIEDMAN SECRET SIGNALING APPARATUS FOR AUTOMATICALLY ENCIPHERING AND DECIPHERING MESSAGES Filed April 14, 1922 8 Sheets-Sheet 2 Gramm,

Jam 13, 1925.

W. F. FRIEDMAN SECRET SIGNALING APPARATUS FOR AUTOMATICALLY ENCIPHERING AND DECIPHERING MESSAGES Filed April 14, 1922 8 Sheets-Sheet :s

`lan. '13, 1925.

W. F. FRIEDMAN SECRET SIGNALING APPARATUS FOR AUTOMATICALLY ENCIPHERING AND DECIPHERING MESSAGES Filed April 14 1922 8 Sheets-Sheet 4 w .www

atkozmtj Jan. 13, 1925. 1,522,775

W. F. FRIEDMAN SECRET SIGNALING APPARATUS FOR AUTOMATICALLY ENCIPHERING AND DECIPHERNG MESSAGES Filed April 14, 1922 8 Sheets-Sheet 5 WIN/'0m F Fra/mm1 lmmw W.v F. FRIEDMAN Jan, 13, 1925.

Filed April 14 1922 SECRET SIGNALING APPARATUS FOR AUTOMATICALLY ENCIPHERING AND DECIPHERNG MESSAGES Janl 13, 1925.

W. F. FRIEDMAN SECRET SIGNALING APPARATUS FOR AUTOMATICALLY ENCIPHERING AND DECIPHERNG MESSAGES Filed April 14, 1922 8 Sheets-Sheet 7 Jan, 13, 1925. 1,522,775

W. F. FRIEDMAN SECRET SIGNALING APPARATUS FOR AUTOMATICALLY ENCIPHERING AND DECIPHERNG MESSAGES Filed April 14, 1922 8 Sheets-Sheet 8 z x x Nm lq Nn VIN I I I @ttor um? Patented Jan. 13, 1925.

UNITED STATES PATENT oFFlcE.

SECRET-SIGNALING APPARATUS FOR AUTOMATICALLY ENCIPHERING AND DECIPHERIN G MESSAGES. 1

Application filed Aprily 14, 1922. Serial No. 552,578.

To all whom it may concern.'

Be it known that WILLIAM F. F RIEDMAN, citizen of .the United States, residing at Washington, new anduseful Improvements in Secret-Signaling Apparatus for Automatically Enciphering and Deciphering Messages, of which the following is a specification.

This invention relates to improvements in secret signaling systems, more particularly to electrical apparatus for the automatic encipherment, transmission, reception and decipherment of messages, and has for its object the provision of apparatus of Such arrangement as will insure a higher degree of secrecy than is the case vin the heretofore prevalent apparatus. The invention is here illustrated as applied to a well-known form of printing telegraph systems but is applicable to other signaling systems, as will readily be understood.

As constituted at present printing telegraph machines adapted for the automatic encipherment and decipherment of messages employ but one arrangement or combination of connections for establishing the necessary electrical circuits concerned directly in the encipherment and decipherment of messages, a condition which greatly facilitates decipherlnent ofthe messages by unauthorized persons. Such unauthorized decipherment is very greatly complicated and rendered almost impossible if the arrangements or combinations of connections in the various enciphering and deciphering circuits aremade susceptible of variation at the will of the correspondents, a condition accomplished through the instrumentalities of my ini vention.

In order that the invention and its mode of application may be readily understood by persons skilled in the art, I have, in the accompanying illustrative drawings, and in the detailed following description based thereon,` set forth several embodiments of the same.

In these drawings Figure 1 is a diagrammatic view of the circuits concerned directly in the enciphering and deciphering operations as constituted in the heretofore prevalent apparatus.

D. C., has invented certain,

Figure 2 is a diagrammatic view of one form of modified circuits whereby a total of one hundred and twenty different sets of electrical circuits for encipherin and deciphering messages are madepossi le, any one of which may be selected and agreed up`on for use at the will of the correspondents.

Figures 3, 4, 5, 6, and 7 are diagrammatic views of other forms of modified circuits whereby a similar number of different sets of combinations of circuits may be obtained as in Figure 2.v

Figure 8 is a diagrammatic view of a modified form of circuits concerned in the transmission and reception of signals, whereby a total of one hundred and twenty different sets of electrical circuits for transmitting and receiving the signals are made` possible, any one of which may be selected for use at the will of the operator.

In these drawings, only such parts of the apparatus as are necessary to an understanding of my invention are illustrated, all other parts required in the proper operation of the apparatus being well known. Furthermore, in order that my invention be understood, it is necessary to give a brief description of the mechanics of the encipherment and decipherment operations in the heretofore existent apparatus.

Having more particular reference to the drawings, in connection with which like characters of reference will designate corresponding parts thereof, A, B, and C are transmitters of a form well known in rinting telegraph apparatus, controlled by perforated tapes containing perforatons disposed transversely across the tape in such combinations as to allow each letter of the alphabet and certain functions of a printing mechanism to be represented by a particular combination of perforations known as code signals. Thus, the letter A, for example, is represented by perforations in the first and second positions across the tape, and the code signal for that letter may be represented by -l- Where represents a positive current impulse, and represents a negative current impulse, although it is to be understood that an open and closed circuit method of operation may be used instead of positive and negative current lmpulses, in which case represents a closed or marking impulse and re resents an open or spacing impulse. T e letter B 'is represented by perforations in the first, fourth and fifth positions-across the tape, and the code signals therefor are and so on. Each transmitter is provided with a set of five movable contacts which vibrate between and make contact with two bus-bars which are connected to the positive and negative poles of a battery, or to battery and ground 1n the case of the open and closed circuit method of operation. In transmitter A the two bus-bars are designated as A21 and A22, positive and negative, respectively; the vibrating contacts are designated as A1,

` A2, A2, A1 and A5. In transmitters B and C the corresponding bus-bars are designated as B21 and B22, C21 and C22, respectively; the sets of vibrating contacts are designated as B1 to B5 and C1 to C5, respectively. Transmitters A and B will be desi ated also as the key-tape transmitters because they arecontrolled by two tapes which constitute the key for the encipherment and decipherment of the messages; transmitter C will be designated also as the message transmitter because it is controlled by a tape bearing the plain text message in the case of encipherment, or the cipher message, in the case of decipherment.

Transmitters A and B jointly control the operation of relays 1, 2, 3, 4, and 5, which are known form, and which will hereafter be designated as the key relays since they are controlled by the key-tape transmitters A and B. Relays 6, 7, 8, 9 and 10, of known form and designated hereafter as the cipher relays, are controlled by the jointl operation of contacts C1 to C5 and the armatures 23 to 27 of relays 1 to 5. Numerals 11, 12, 13, 14 and 15 are the magnets of an automatic tape perforator, deslgnated hereafter as the machine perforator. These magnets control the operation of punches which perforate the tape produced forthe cipher message, andg will be designated hereafter as the punch magnets. They are actuated by circuits established through the energiz` ing of cipher relays 6, 7, 8, 9 and 10. Numerals 16, 17, 18, 19 and 20 are the magnets of the printing mechanism which ty s the letters on a sheet or roll of paper.

ese magnets perform the function of selecting the specific character to be printed and will be designated hereafter as the selecting magnets. They are also actuated by vcircuits established through the operation of cipher relays 6, 7, 8, 9 and 10.

Referrin now to transmitter A, Figure 1, bar A21 1s connected to the positive pole 0f battery, 39, bar A22 is connected to the negative pole of battery 39. Each of the vibrating contacts A1, A2, A2, A* and A can touch either A21 or A22 and thus determine the polarity of current transmitted "to the lines leading to the relays 1, 2, 3, 4, and 5. Which of the two bars A21 or A22 any of these vibrating contacts touches is determined by the perforations'in the tape; if there is a perforation in position 1 in the tape, then contact A1 touches bar A21; if there is no perforation in position 1 of the tape, then contact A1 touches bar A22. The same applies to contacts A2, A2, A2 and A, which are governed by the presence or absence of perforations in positions 2, 3, 4 and 5, respectively across the ta e. What has been said of the operation o transmitter A applies equally to the operation of transmitter B with its corresponding or homolo ous vibrating contacts B1, B2, B3, B4I an B5 which make contact with either bar B21, which is connected to the positive pole of battery, or B22, which is connected to the negative pole of battery. The two sets of contacts A1 to Al and B1 to B5 are operated synchronously so that all the contacts touch the bars at exactly the same moment, though of course, some of them touch the bars of posltive polarity, the others touch the bars of negative polarity, depending upon the particular combina-tions of perforations in theI respective tapes going through the transmitter at that moment.

It will be noted that the circuits of relays 1, 2, 3, 4 and 5 really constitute five independent circuits. The circuit of relay 1, for example, is that in which the pair of corresponding or homologous contacts A1 and B1 are the determining members; the circuit of relay 2 is that in which the pair of homologous contacts A2 and B2 are the determining members, and so on. Each pair of homologous contacts can therefore affect one and only one of the key relays, viz, that key relay whose operation is controlled by that particular pair of homologous contacts.

One/of the four following conditions with respect to the operation or non-operat-ion of relay 1 may exist at a given moment:

(1) Contact A1 may be touching bar A21 when contact B1 is touching bar B22. An

electrical circuit is thereby established from` positive pole of battery 39, through A21, A1, Winding of relay 1, B1, B22, to negative pole of battery gized.

(2) Contact A1 may be touching bar A22 when contact B1 is touching bar B21. An electrical circuit is thereby established from positive pole of battery 39 through B21, B1, winding of relay 1, A1, A22, to negative pole of battery 39. Relay 1 is therefore energized.

(3) Contact A1 may be touching bar A21 39. Relay 1 is therefore ener-V when Contact B1 is also touching bar B21.

' No circuit is established for bot-h A1 and B1 when contact B1 is also touching bar B22.

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No circuit is established for both A1 and B1 are touching bars which are of negative polarity, no di'erence in potential exists and relay 1 is therefore not energized.

It is obvious therefore that relay 1 can be operated only when the two homologous contacts A1 and B1 are touching bars of opposite polarity. If contact A1 is touching the bar of positive polarity, then contact B1 must be touching the bar of negative polarity in order to energize relay 1, and vice versa. y

What has been said of contacts A1 and B1 and of relay 1 applies equally to the other homologous pairs of contacts A2 and B2, A3 and B3, A4 and B4, A5 and B5, and their respective relays, 2, 3, 4, and 5, Furthermore, as has already been stated, as the circuits are arranged in the heretofore prevalent apparatus, relays 1, 2, 3, 4, and 5 are -absolutely independent of each other, and

are energized or unenergized depending only upon the polarity of the terminals of the windings of each relay as controlled by each homologous pair of contacts A1 and B1, A2 and B2, A3 and B3, A4 and B4, A5 and B5, respectively.

Transmitter C in FigureV 1 functions in exactly the same manner as do transmitters A and B and in synchronism with them; a

` perforated tape passing through transmitter C determines which of' the two bars C21 and C22, connected to positive and negative poles, respectively, of battery 40. aretouched by its vibrating contacts C1, C2,4 C3, C4 and C5 for each character. These contacts operate synchronously with the lcontacts in transmitters A and B.

The conductors, 60, leading from contacts C1, C2, C3, C4, and C5 form one set of terminals of the windings of cipher relays 6, 7, 8, 9 and 1Q, respectively. The armatures of key relays 1, 2, 3, 4, and 5 form the other set of terminals of the windings of cipher relays 6, 7 8, 9, and 10.

One of the four following conditions with respect to the operatio-n or non-operation of cipher relay 6 may exist at a given moment:

(l) Contact C1 may be'touching bar C21 when relay 1 is unenergized. The normal or unat-tracted position of the armature of relay 1 is such as to make contact with negative pole of battery 40. Therefore the circuit for energizing` relay 6 is completed, for a current starts flowing from positive pole of battery 40, through bar C21, contact C1, winding of relay 6, armature of relay 1 to negative pole of battery 40, and relay 6 is therefore energized.

(2) Contact C1 may.V be touching bar C21 when relay 1 is energized. The position ot' 'armature 23 of relay 1 when relay 1 is energized is such as to make contact with positive pole of battery 40. Therefore the circuit for energizing relay 6 is not completed, for both terminals of the winding of this relay are then connected with the positive poleJ of battery 40, and relay 6 therefore remains unenergize (3) Contact C1 may be touching bar C22 when relay 1 is unenergized. The circuit for energizing relay 6 is not completed, for both terminals of the windingof this relay are then connected with the negative pole of battery 40, and relay 6 therefore remains unenergized.v

(4) Contact C1 may be touching bar C22 when relay 1 is energized. The circuit for energizing relay 6 is therefore completed. for a current starts iowing from positive pole of battery 40, through armature 23 of relay 1, winding of relay 6, contact C1. bar C22, to negative pole of battery 40, and relay 6 is therefore energized.

VIt is obvious therefore that relay 6 can be energized only when conditions 1) and (4) above obtain, that is, when the terminals of the winding of this relay are connected to both polarities of the battery. What has been said of cipher relay 6 applies also to cipher relays 7, 8, 9 and 10, controlled by armatures 24, 25, 26, and 27 and contacts C2, C3, C* and C5.

It is likewise apparent here that as the circuits are arranged in the heretofore prevalent apparatus, as shown in Figure 1, cipher relays 6, 7, 8, 9 and 10 are absolutel)Y independent of each other, and are energized or unenergized depending only upon the polarity of the terminals of the winding of each relay as controlled by each homologous pair of contacts C1 and armature 23, C2 Vand armature 24, C3 and armature 25, C1 and armature 26, C5 and armature 27, these armatures being of course controlled by the pperation of the five independent key reays.

When cipher relay 6 is energized, the armatures 28 and 29 are attracted and thus make contact with positive pole of battery 0; a current flows from positive pole of battery through armatures 28 and 29, the windings of magnets 11 and 16, and, if keys 66 and 67 are closed, to the negative pole of battery 70, thus completing the circuit and operating punch magnet 11 and selecting magnet 16. What has been said of the operation of cipher relay 6 and magnets 11 and 16 applies also to the operation of cipher relays 7, 8, 9 and 10, punch magnets 12, 13, 14, 15, and selecting magnets 17 18, 19 and 20.

lll)

' mitter C; and since the operation of mag-2 ISOv the positions of the vibrating contacts iny transmitters A and B, and since the operation or non-operation of cipher relays 6 to l() is determined by the operation or nonoperationof key relays 1 to 5 in conjunction with the positions of the contacts in transnets 11 to 20 is determined by the operation of cipher relays 6 to 10, it is clear that the cipher tape perforated, or the characters printed by the printer, are thus (the resultants of they interaction of all the electrical circuits controlled jointly by all three transmitters A, B, and C, through the intermediacy of the relays 1 to 10 controlled by these transmitters.

Let us suppose that at a given moment the character X, normal code -irepresented by perforations at positions 1, 3, 4, and 5 across the tape is passin through transmitter A, and character Y normal code signal represented by perforations at positions 1, 3 and 5 across a second tape, is passing through transmitter B. Contact A1 will touch bar A21, and contact B1 will touch bar B21; both contacts will therefore be touching bars of positive polarity; no circuit is established and therefore relay 1 is not energized. Contacts A2 and B2 will both be touching bars of negative polarity; no circuit is established and therefore relay 2 is not energized. Contacts A3 and B3 will both be touching bars of positive polarity; no circuit is established and hence relay 3 is not energized. Contact A4 will be touching bar A21, of positive4 polarity, contact B4 will be touching bar B22 of negative polarity; a circuit is completed and relay 4 is therefore energized. Contacts A5 and B5 will bot-h be touching bars of positive polarity; no circuit is completed and therefore relay 5 is not energized. The direct resultant ofthe interaction of characters X and Y when simultaneously passing through transmitters A and B, is that only relay 4 is energized, relays 1, 2, 3, and 5 remaining unenergized. Armatures 23, 24, 25 and 27 will therefore be making contact to negative pole of battery 40, armature 26 to positive pole of bat-y tery 40. If now, at the same instant character Z, normal code signal represented by perforations in positions 1 and 5 across a third tape is passing through si nal n..

(1) Contact C1' is against bar C21, which is connected to positive pole of battery 40, A

armature 23 1s connected to negative pole of battery 40. Relay 6 is lthereiore energized.

(2) Contact C2 is against bar C22, which is connected to negative pole of battery 40, armature 24 is connected tone ative pole of battry- 40. Relay 7 is there ore not energlze (3) Contact C3 is against bar C22, which is connected to negative pole of battery 40, armature 25 is connected to negative pole. of battery 40. Relay 8 is therefore not energized.

(4) Contact C4 is against bar C22, which is connected to negative pole of battery 40,

armature 26 is connected to positive pole of battery 40. Relay 9 is therefore energized. A(5) Contact C5 is against bar C21, which is connected to positive pole of battery 40, armature 27, is connected to negative pole of battery 40. Relay 10 is therefore energized.

If key 66 is closed, key 67 open, magnets 11, 14, and 15 will be operated, perforating holes in positions 1,-4 and 5 across the cipher tape which will represent the letter B, the normal code signall for ywhich is -l- +3 The cipher resultant of the interaction of letters X, Y, and Z, will therefore be the letter 13. If key 67 is'y closed, magnets 16, 19 and 20 will be operated and this will result in the-selection of the letter B for printing by the printing mechanism.

As soon as the resultant of one set of characters passing through the two keytape'transmitters and the message transmitter has been perforated, a new set of characters is presented at the three transmitters and another character is perforated by the machine perforator, and so on until a cipher tape is produced which represents the resultants of the electrical combination of two-tapes and the message tape. vThis cipher tape is then transmitted over the line in the usual inanner and at the receiving end a duplicate ofthe cipher tape transmitted is perforated in a Well-known manner by an automatic perforator. The duplicate cipher tape thus prepared is then run through message transmitter C together with key tapes which are duplicates of those at the transmitting end and which are run through key-tape vtransmitters A and B. This effects the decipherment of the message and it may be perforated by the machine perforator or printed by the printer. To illustrate the steps in the decipherment, let us follow through the decipherment of the letter B Whose encipherment I have just demonstrated. Letters X and Y will be presented at key-tape transmitters A and B, and the resultant; the interaction vof letters result upon key relays 1 to 5 will of course be exactly the same as before, relay 4 being the only one energized, and armatures 23, 24, 25 and 27 making contact to negative pole of battery 40, armature 26, topositive pole of battery 40. If now the character B represented as We have seen, by perforations in positions 1, 4, and 5 across the tape, is passing through transmitter C, then We will have following:

(1) Contact C1 is against bar C21, which is connected to positive pole of battery 40, armature 23 is connected to negative pole of .battery 40. Relay 6 is therefore energlzed.

(2) Contact C2 is against bar C22, which is connected -to negative pole of battery 40, armature 24 is also connected to negative pole of battery 40. Relay 7 is therefore not energized. y y

(3) Contact C3 is against bar C22, which is connected to'negative pole of battery 40, armature 25 is also connected to negative pole of battery 40. Relay 8 is therefore not energized.

(-4) Contact C4 is against bar C21, which is connected to positive pole of battery 40.

Armature 26 is also connected to positive@ pole of battery 40. Relay 9 is therefore not energized.

(5) Contact C5 is against bar C21, which is connected to positive pole of battery 40, armature 27 is connected to negative pole of battery 40. Relay 10 therefore is energized. l

If keys /66 and 67 are closed magnets 11, 15, 16 and 2() will be operated, and the character perforated and printed is s -iwhich is Z. Thus, cipher character B has been correctly deciphered by key characters X and Y into plainetext character Z.

Now it is clear that in encipherment the printing of the letter B, or the perforation of a cipher tape with perforations representing the letter fB,as the resultant of the interaction of letters X,`Y, and Z in transmitteis A, B and C, respectively, and

' in decipherment the perforation of a plaintext tape with perforations representing the letter Z, or the printing of the letter Z as the resultant of the interaction of letters X, Y, andB in transmitters A, B, and C, respectively, is dependent upon the arrangen'ient of the circuits shown in Figure 1. The machines as at present constituted employ but one set or combination of enciphering circuits, and ypermit of no changes in the connections between the various contact points, relays and magnets concerned directly in the enciphering operations. The interaction of letters X, Y and Z will always yield B as the cipher Y and B will always yield Z as the deciphered character. The same holds true with respect to the various reult-ants of all other combinations of letters: these resultants in the apparatus as constituted heretofore, are alwaysconstant in nature, dependent only upon the letters which enter into the reaction.

The principal feature of Figure 1 to which .attention is directed in connection with the essential nature of my invention is that. final operation of magnets 11 to 20 is determined by the positions of three sets of live homologous contacts in all three transmitters A, B, and C, as controlling relays corresponding to homologous pairs of contacts. Magnets 11 and 16, for example, are operated by a circuit controlled by cipher relay 6, the operation 0f which is in turn controlled by the positions of the three homologous contacts A1, B1 and'C1.y

Figure 2 shows a switching or connection-changing device E, inserted in the conductors 61, connecting contacts A1, A2, A, A4 and A's to the windings of the five rela s 1, 2, 3, 4, and 5. -This device E may any one of a number of forms of switchboards or connection-changing devices, preferably one of the telephone switchboard type, with plugs and jacks, but any other form of connection-changing apparatus may be used. By means of this switchboard it now becomes possible to connect the set of five contacts A1, A2, A2', A* and A5 with the windings of the ve relays 1, 2, 3,4, and 5 in 120 different ways or permutations, instead of one and only one arrangement of connections, as is the case in the heretofore prevalent apparatus. In Figure 2 the particular permutation of connections shown may be designated by the number 35214, indicating that contact A1 is now in the circuit of relay 3; contact A2, in that of relay 5; contact A2, in that of relay 2; contact A4, in that of relay l; and contact A, in that of relay 4.

Lethus now consider what happens when letters X, Y, and Z are passing through transmitters A, B, and C, respectively. The following is a summary of the reactions which occur in Figure 2:

`(1) Contact A1 is against bar A21, which is connected to positive pole of battery 39. A1 is connectedsto jack 41to plug 46, to 'jack 53, to winding ofj'relay 3, to contact B8, which is then against bar B21, which is connected to positive pole of battery 39. Relay 3 therefore remains unenergized; hence armature 25 remains in its unattracted position, making contact with negative pole of battery 40. Contact C2 is then against bar C22, which is connected to negative pole of battery 40. Relay 8 therefore remains unenergized; hence armature 32 remains .in its unattracted position, making no contact to battery 70. Hence magnet 13 remains inoperative and no perforation is made'atposition 3 across the tape.

(2) Contact A2 is against bar A22, which is connected to negative pole of battery 39. A2 is connected to jack 42, to plug 47, yto tck 55, to winding of relay 5, to contact 5, which is then against bar B21, which is connected to positive pole of battery 39. A circuit is completed through the winding of relay 5 and it is therefore energized; hence armature 27 is attracted, making contact with positive pole of battery 40. Contact Cs is then against bar C21, which isalso connected with positive pole of battery 40.

No circuit is completed through relay 10 and it therefore remains unenergized; hence armature 36 remains in its unattracted position, making no contact to battery 70. Hence magnet 15 remains inoperative and no perforation is made at position 5 across the tape. i

(3) Contact A3 is against bar A21, which is connected to positive pole of batteryK 39. A3 is connected to jack 43, to plug 48, to

v tck 52, to winding of relay 2, to contact 51, winding which is then against bar B22, which is connected to negative pole of battery 39. A circuitl is completed through the winding of relay 2, and it is therefore energized; hence armature 24 is attracted, making contact with positive pole of battery 40. Contact C2 is then against bar C22, which is connected to negative pole of battery 40. A circuit is completed through the winding of relay 7, and it is therefore energized; hence armature 30 is attracted, making contact to positive pole of battery 70, and a cur-f rent flows from positive terminal of battery 70 through armature 30,y winding of magnet 12 to neglative pole of battery 70. Magnet 12 is t ereforeoperated and a perforation is made in p'osition 2 across the ta e.

I(4) Contact A4 is against bar A21., which is connected to positiver pole of battery 39. AI is connected to jack 44, plug y49, 'ack of relay 1, ycontact B1, w ich is then against bar B21, which is connected to positive pole of battery 39.` No circuit is completed and relay 1 remains therefore unenergized; hence amature remains in its unattracted position, maklng contact with negative pole of battery Contact C1 is then against bar C21, which is connected to ositive .pole of battery 40. A circuit is t'erefor completedl through-the winding of relay 6 and it is therefore energized; hence armature 28 1s attracted,

makin contact with positive ypole 'of battery .70 an a current iows from positive ole of batteryY 70 through armature 28, Win ing of magnet 11 to negative pole 0f battery 70.

Magnet 11 is operated and a perforation is made in position 1 across the tape.

(5) Contact A5 is against bar A21, which is connected to positive pole of battery 39. A5 is connected to jack 45, to plug 50, to 'Eck 54, to winding of relay 4, to contact 4, which is then against bar B22, which is connected to negative pole of battery 39. A circuit is therefore completed through the winding of relay 4, and it is therefore nergized; hence armature 26 is attracted, makin contact with positive pole of battery 40. ntact C4 is then against bar C22, which is connected to negative pole of battery 40. A circuit is therefore completed through the winding of relay 9 and it is therefore ener ized; hence armature 34 is attracted, maklng contactto positive pole of battery 70, and a current flows from positive pole of battery 70 through armature 34, winding of magnet 14 to negative pole of battery 70. Magnet 14 is operated and a perforation is made in position 4 across the tape. y

The summary or final result is that perforations are made in positions 1, 2, and 4 across the tape, making the signal and this combination represents the letter J in the conventional code.

Here we see that the cipher resultant of the interaction of -letters X, Y, and Z before, but an altogether different letter, jviz, J The cipher perforator would perforate the combination representing letter J and the printer would select and print the letter J il What has been said about the interaction of this particular combination of letters appliesto all other combinations of letters; the resultants will be diii'erent from those produced by the connections shown in Figure 1. The steps in decipherment are properly modified at the deciphering end since a similar switchboard is inserted in the identical position and is set up for the same permutation of connections yas at-the enciphering end. The decipherment of the letter J by means of key letters X and Y must yield letter Z. v

It is obvious Vof course that this result will be altogether dierent for a different permutation of connections established through E. As said before, 120 different ermutations of connections are possible. It 1s necessar of course that the correspondents shall ave previously agreed upon the the same. `In Figure 2 the connection changi ing device E is shown as inserted between contacts A1, A2, A3, A4, A and the conductors 61 leading to the windings of the relays 1, 2, 3, 4, and.y In Figure 3 the connection changing device E is shown as inserted in the conductors 62 leading from i contacts B1, B2, BS, B, and B5, to the windings of the relays 1, 2, 3, 4, and 5. The

4 cipher resultant of the interaction "of the letters X, Y and Z isnow the code signal as shown in Figure 3 using the saine permutation of connections as before, viz, 35214. The following diagram is a brief method of indicating the reactions in this case: Y

Transmitter B-letter Y Transmitter A-letter X Armatures of key relays 1 Transmitter C-letter Z (,iphcr resultant f Since there will be no indication in the cipher message as to exactly which one of the 120 possible permutations of connections is in effect at a given time, an enemy who intercepts or comes into possession of a cipher' message would not know which one of a series of 120 different sets of resultants apply in the message or messages which he has obtained, thus making the unauthorized decipherment an extremely diicult matter.

In Figure 4 the connection-changing device E is inserted in the conductors 63 leading from armatures 23, 24, 25, 26, 27 to the windings of relays 6. 7, 8, 9 and 10. As in the preceding case, 120 permutations of connections are likewise possible in this case. The cipher resultant of the interaction of letters Y and Z with the permutation of connections, 35214, as before, is now the letter T as shown by the following diagram:

1 2 s 4 5 TransmitterA-lctter1' In Transmitter Bi-lett-eVY Armatures of key relays 1 `I 'lransmitterC-lctter Z ('ipher resultant Transmitter A-letter X +I Transmitter B--letter Y Armatures of lrey relays 1 f to 5 M Transmitter C-letter Z Cipher resultant In Figure 6, the connection-changing device E is inserted in the conductors 64 leading from armatures 28, 30, 32, 34, 36 to the windings of lnagnets 11, 12, 13, 14, and 15. As in the preceding case, 120 different permutations of connections are likewise possible in this case.

In Figure 7, the connection-changing device E is inserted in the conductors 65 leading from armatures 29, 31, 33, 35, 37 to the windings of magnets 16, 17, 18, 19 and 20. As in the preceding case, 120 different permutations of connections are likewise possible in this case.

The connection changing device ll is shown as inserted in the conductors leading only to the perforator magnets inl Figure 6, and only to the printer magnets in Figure 7, but it is to be understood that if it is desired to print and perforate the same final code signals, similar connection changing devices with identical permutations of connections would have to be inserted simultaneously' in both positions shown in Figures 6 and 7, otherwise the two sets of magnets would act differently, thus producing a perforated tape that would not match the printed message. Usually only one copy would be retained at the transmitting station, either the perforated tape copy or the printed from copy.

It is obviousof course. that there are only 120 different permutations of connections in the Whole system, for the electrical results of a permutation produced lby inserting the connection-changing device E in one position can be duplicated by the electrical results of a permutation produced by inserting the connection-changing device E in another l location.

Since the operations of the various parts of the whole apparatus are the same for both encipherment and decipherment, the insert-ion of the connection-changing device at any of the places shown in the diagrams will serve for decipherment as well as encipherment so long as the permutation of connections that is used at both ends during a given period is the Same.

The preceding Figures l to 7 apply to that l `unchanged signal. "connectlon changing device E as` inserted inv method of operation in which the encipherment and decipherment of messages is acn complished by local sets, the messages transmitted over the line being transmitted in exactly the same manner as though they were ordinary intelligible messages, with the exception that instead of printing the received messages directly on a printer they must be received and perforated on a tape and this tape message is then deciphered by the local set at the receiving end, in a well-known manner. It is possible, however, to encipher and decipher the messages without the intermediacy of local sets at the two ends, by enciphering and transmitting a message coincidently at the ysending end, and receiving and deciphering it coincidently at the receiv' ing end. Todo this, it is necessary, as shown in Fig; 8, to lead conductors 64 to the segments of the transmitting face of a wellknown form of distributor for enciphering and transmitting coincidently, and conductors 60 to the segments of the receiving face of a similar distributor operating synchronously with the sending distributor for receiving and decipherin coincidently. In Figure 8 which shows t e arrangements for this system of operation, the distributors which are of well-known form, .are not shown. In this method of operation, when enciphering and transmittin coincidentl the set of keysl 71 in the con uctors 64 lea ng to the segments 1 to 5 of the'transmitting face of the distributor are closed, and

the set of keys 72 in the conductors 60 leading to the segments 1" to 5 oflthe receiving face of they distributor are opened., It is not really necessary to have a copy of the transmitted messages prepared at the transmitting station, but if it is desired to retain a perforated tape copy of the transmittedmessage, switch 66 is closed, thus allowing perforator magnets 11 to 15 to operate; but switch 67 is opened throwing printer ma nets 16 to 2() out of operation as there wo d be no need of having a printed copy of the This figure shows the the conductors leading to the segments of the transmitting face of the distributor, and

v also to the perforator magnets. Thus, the

original code signal ,-l as set up at relays 6 to 10 is changed to. -lby E and is transmitted and perforated as the latter. Herel again a total of 120 permutations of connections between armatures 28, 30, 32, 34, 36 and segments 1 to 5 and magnets 11 to 15 is possible. Figure 8 also shows the insertion of the connection changing device E- in the conductors leading from the segments of the receiving face of the distributor, so that the received signals may be translatedbacky into a form to correspond with their original form as set up at relays 6 to 10 at the transmitting end.

In receiving, transmitter C takes no part in the operation, transmitter contacts C1 to C5 being thrown to a neutral position by alever arm now shown inthe drawing. Switch 67 is closed, allowing printer magnets 16 to 20 to function. If a-perforated received message is desired, switch 66 is closed, but the connections in E are arranged to connect magnet 11 with armature 28, magnet 12 with armature 30, etc., that is, the arrangement is as if no switchboard E were inthe circuit at that point. The permutation ofconnections at E as shown in Figure 8 is such as to chan e the signal as it comes o the segments 1 to 5 into the signal -lwhen it reaches conductors 60 leading to rela 6 to 10. Thus, the unmodified' signal originally set up at the cipher relays 6 to 10 at the transmitting end, is brought back into the same signal when it reaches the corresponding cipher relays at the receiving end.

Figures 3, 4, 5, 6, 7, and 8 are meant to show only that the connection-changin device E may be inserted in various other p aces than those shown in Figure 2. In the specified embodiment of my invention herein'disclosed,` I have Eillustrated but two key tape transmitters, five key relays and five cipher relays adapted to encipher `or decipher messages, but it is obvious that more key transf mitters may be provided to afect the operation of the key relays and the cipher relays; and one or more connection-changing devices may be inserted in the circuits concerned in the additional key transmitters.

Manifestly, the n. arrangements` shown throughout are capable of modification, and` such modications as are within the scope of my claims, I consider within the spirit of my invention. i y

I claim: i

l. An electrical enciphering and deciphering system in which the cipher characters are the resultants of the superimposition and combination of a set of electrical :conditions governed by the characters of a pair of key tapes upon the set of electrical conditions governed by message characters, comprising a set of key tape transmitter relays controlled by a pair iof key tape transmittersv through which said key tapes are passed, a

set of cipher relays controlled jointly by said key tape transmitter relays and the message transmitter, a sending and receiving distributor, a printer, an automatic tape perforator, means for transposing in a plurality of ways, within each set, any one of a set' of conductors involved in establishing the code combinations equivalent to the characters transmitted, for the purpose of changin the characters that would normally be pro uced by the superimposition of the set of electri-y cal conditions governed by the kY tapes upon the message characters,

2. An electrical enciphering and deciphering system, in which the cipher characters are the resultants of the superimposition and combination of a set of electrical conditions governed by the characters of a pair of key tapes upon the electrical conditions governed by the characters of the message, comprising a set of key tape transmitter relays controlled bya pair of key tape transmitters through which said key tapes are passed, each of the key tape transmitters being provided with a set of vibratin contacts, a set of cipher relays controlled jointly by the key tape transmitter relays and a message transmitter, means for changing, in a lurality of ways, the connections between the windings of the key tape transmitter relays and the set of vibrating contacts of one of the key tape transmitters for the purpose of changing the characters that would nor# mally be produced by the superimposition of a set of electrical conditions governed by the key Atapes upon the message characters.

In testimony whereof I afiix my signature.

WILLIA,M F. F RIEDMAN. 

